“…The included 13 studies were cohort or case–control designs, with retrospective data extracted from either electronic databases or hard copy medical charts. Five of the studies were conducted in Australia (Bail et al, 2013; Draper, Karmel, Gibson, Peut, & Anderson, 2011; Harvey, Mitchell, Brodaty, Draper, & Close, 2016; King, Jones, & Brand, 2006; Scandol, Toson, & Close, 2013), three in the United States of America (Holmes, Jones, & Laughon, 2017; Lagu et al, 2016; Sherzai et al, 2016) and one each in the United Kingdom (Fogg, Meredith, Bridges, Gould, & Griffiths, 2017), Spain (Guijarro et al, 2010), Taipei (Hu, Liao, Change, Wu, & Chen, 2012), Finland (Jämsen, Peltola, Puolakka, Eskelinen, & Lehto, 2015) and Germany (Rösler, Krause, Niehuus, & von Renteln‐Kruse, 2009). The sample size ranged from 26 to over 13,000,000 patient admissions due to the use of nationwide data sets.…”